Method and system for configurable data rate thresholds for energy efficient ethernet

ABSTRACT

Aspects of a method and system for programmable data rate thresholds for energy efficient Ethernet are provided. In this regard a data rate for communicating over a network link may be selected from a list of permissible data rates, where the list of permissible data rates may be determined based on traffic associated with the network link. Each of the permissible data rates may be determined based on, for example, past and/or expected traffic on the link, a type of traffic associated with the link, and/or one or more applications associated with the link. The selected data rate may be achieved by controlling a number of physical channels of the link that are utilized for communications over the link, voltage and/or current levels utilized for signaling on the link, a signal constellation utilized for representing data on the link, and/or an inter-frame gap or inter-packet gap utilized on the link.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This patent application makes reference to, claims priority to and claims benefit from U.S. Provisional Patent Application Ser. No. 60/979,433 filed on Oct. 12, 2007.

The above stated application is hereby incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

Certain embodiments of the invention relate to networking. More specifically, certain embodiments of the invention relate to a method and system for configurable data rate thresholds for energy efficient Ethernet.

BACKGROUND OF THE INVENTION

With the increasing popularity of electronics such as desktop computers, laptop computers, and handheld devices such as smart phones and PDA's, communication networks, and in particular Ethernet networks, are becoming an increasingly popular means of exchanging data of various types and sizes for a variety of applications. In this regard, Ethernet networks are increasingly being utilized to carry, for example, voice, data, and multimedia. Accordingly more and more devices are being equipped to interface to Ethernet networks.

As the number of devices connected to data networks increases and higher data rates are required, there is a growing need for new transmission technologies which enable higher data rates. Conventionally, however, increased data rates often results in significant increases in power consumption. In this regard, as an increasing number of portable and/or handheld devices are enabled for Ethernet communications, battery life may be a concern when communicating over Ethernet networks. Accordingly, ways of reducing power consumption when communicating over Ethernet networks may be needed.

Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method is provided for configurable data rate thresholds for energy efficient Ethernet, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims.

These and other advantages, aspects and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an Ethernet connection between a local link partner and a remote link partner, in accordance with an embodiment of the invention.

FIG. 2 is a block diagram illustrating an exemplary Ethernet over twisted pair PHY device architecture comprising a multi-rate capable physical block, in accordance with an embodiment of the invention.

FIG. 3 is a diagram illustrating an exemplary system enabled for reduced power consumption during periods of low link utilization, in accordance with an embodiment of the invention.

FIG. 4 is a block diagram illustrating transmission of signals utilizing a reduced number of signal levels, in accordance with an embodiment of the invention.

FIG. 5 is a diagram illustrating transmission of signals utilizing a reduced signal constellation, in accordance with an embodiment of the invention.

FIG. 6 is a diagram illustrating adjusting inter-frame gap to control data rates on an Ethernet link, in accordance with an embodiment of the invention.

FIG. 7 is a diagram illustrating data rate transitions on a network link with configurable data rate thresholds, in accordance with an embodiment of the invention.

FIG. 8 is a flowchart illustrating exemplary steps for establishing and selecting a programmable data rate, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention may be found in a method and system for a configurable data rate threshold for energy efficient Ethernet. In this regard a data rate for communicating over a network link may be selected from a list of permissible data rates, where the list of permissible data rates may be determined based on traffic associated with the network link. Each of the permissible data rates may be determined based on, for example, past and/or expected traffic on the link, a type of traffic associated with the link, and/or one or more applications associated with the link. The selected data rate may be achieved by controlling a number of physical channels of the link that are utilized for communications over the link, voltage and/or current levels utilized for signaling on the link, a signal constellation utilized for representing data on the link, and/or an inter-frame gap or inter-packet gap utilized on the link. The selected data rate may be the lowest rate in the list that may still be greater than a demand on the link. A first portion of the list may be utilized for ingress communication and a second portion of the list may be utilized for egress communication.

FIG. 1 is a block diagram illustrating an Ethernet connection between a local link partner and a remote link partner, in accordance with an embodiment of the invention. Referring to FIG. 1, there is shown a system 100 that comprises a local link partner 102 and a remote link partner 104. The local link partner 102 and the remote link partner 104 may communicate via a cable 112. In an exemplary embodiment of the invention, the cable 112 may comprise up to four or more physical channels, each of which may, for example, comprise an unshielded twisted pair (UTP). The local link partner 102 and the remote link partner 104 may communicate via two or more physical channels in the cable 112. For example, Ethernet over twisted pair standards 10BASE-T and 100BASE-TX may utilize two pairs of UTP while Ethernet over twisted pair standards 1000BASE-T and 10GBASE-T may utilize four pairs of UTP. In this regard, however, aspects of the invention may enable varying the number of physical channels via which data is communicated.

In an exemplary embodiment of the invention, the link partners 102 and/or 104 may comprise a twisted pair PHY capable of operating at one or more standard rates such as 10 Mbps, 100 Mbps, 1 Gbps, and 10 Gbps (10BASE-T, 100GBASE-TX, 1GBASE-T, and/or 10GBASE-T); potentially standardized rates such as 40 Gbps and 100 Gbps; and/or non-standard rates such as 2.5 Gbps and 5 Gbps.

In an exemplary embodiment of the invention, the link partners 102 and/or 104 may comprise a backplane PHY capable of operating at one or more standard rates such as 10 Gbps (10GBASE-KX4 and/or 10GBASE-KR); and/or non-standard rates such as 2.5 Gbps and 5 Gbps.

In an exemplary embodiment of the invention, the link partners 102 and/or 104 may comprise an optical PHY capable of operating at one or more standard rates such as 10 Mbps, 100 Mbps, 1 Gbps, and 10 Gbps; potentially standardized rates such as 40 Gbps and 100 Gbps; and/or non-standardized rates such as 2.5 Gbps and 5 Gbps. In this regard, the optical PHY may be a passive optical network (PON) PHY.

The local link partner 102 may comprise a host 106 a, a medium access control (MAC) controller 108 a, and a PHY device 104 a. The remote link partner 104 may comprise a host 106 b, a MAC controller 108 b, and a PHY device 110 b. Notwithstanding, the invention is not limited in this regard. In various embodiments of the invention, the link partner 102 and/or 104 may comprise, for example, computer systems or audio/video (A/V) enabled equipment. In this regard, A/V equipment may, for example, comprise, a microphone, an instrument, a sound board, a sound card, a video camera, a media player, a graphics card, or other audio and/or video device. Additionally, the link partners 102 and 104 may be enabled to utilize Audio/Video Bridging and/or Audio/video bridging extensions (collectively referred to herein as audio video bridging or AVB) for the exchange of multimedia content and associated control and/or auxiliary data.

The PHY devices 110 a and 110 b may each comprise suitable logic, circuitry, and/or code that may enable communication, for example, transmission and reception of data, between the local link partner 102 and the remote link partner 104. The PHY devices 110 a and 110 b may support, for example, Ethernet over copper, Ethernet over fiber, and/or backplane Ethernet operations. The PHY devices 110 a and 110 b may enable multi-rate communications, such as 10 Mbps, 100 Mbps, 1000 Mbps (or 1 Gbps), 2.5 Gbps, 4 Gbps, 10 Gbps, or 40 Gbps, for example. In this regard, the PHY devices 110 a and 110 b may support standard-based data rates and/or non-standard data rates. Moreover, the PHY devices 110 a and 110 b may support standard Ethernet link lengths or ranges of operation and/or extended ranges of operation. The PHY devices 110 a and 110 b may enable communication between the local link partner 102 and the remote link partner 104 by utilizing a link discovery signaling (LDS) operation that enables detection of active operations in the other link partner. In this regard the LDS operation may be configured for supporting a standard Ethernet operation and/or an extended range Ethernet operation. The PHY devices 110 a and 110 b may also support autonegotiation for identifying and selecting communication parameters such as speed and duplex mode.

In various embodiments of the invention, the PHY devices 110 a and 110 b may comprise suitable logic, circuitry, and/or code that may enable transmission and/or reception at a high(er) data in one direction and transmission and/or reception at a low(er) data rate in the other direction. For example, the local link partner 102 may comprise a multimedia server and the remote link partner 104 may comprise a multimedia client. In this regard, the local link partner 102 may transmit multimedia data, for example, to the remote partner 104 at high(er) data rates while the remote link partner 104 may transmit control or auxiliary data associated with the multimedia content at low(er) data rates.

The data transmitted and/or received by the PHY devices 110 a and 11Ob may be formatted in accordance with the well-known OSI protocol standard. The OSI model partitions operability and functionality into seven distinct and hierarchical layers. Generally, each layer in the OSI model is structured so that it may provide a service to the immediately higher interfacing layer. For example, layer 1, or physical layer, may provide services to layer 2 and layer 2 may provide services to layer 3. The data transmitted may comprise frames of Ethernet media independent interface (MII) data which may be delimited by start of stream and end of stream delimiters, for example.

In an exemplary embodiment of the invention illustrated in FIG. 1, the hosts 106 a and 106 b may represent layer 2 and above, the MAC controllers 108 a and 108 b may represent layer 2 and above and the PHY devices 110 a and 110 b may represent the operability and/or functionality of layer 1 or the physical layer. In this regard, the PHY devices 110 a and 110 b may be referred to as Physical layer transmitters and/or receivers, physical layer transceivers, PHY transceivers, PHYceivers, or PHY, for example. The hosts 106 a and 106 b may comprise suitable logic, circuitry, and/or code that may enable operability and/or functionality of the five highest functional layers for data packets that are to be transmitted over the cable 112. Since each layer in the OSI model provides a service to the immediately higher interfacing layer, the MAC controllers 108 a and 108 b may provide the necessary services to the hosts 106 a and 106 b to ensure that packets are suitably formatted and communicated to the PHY devices 110 a and 110 b. During transmission, each layer may add its own header to the data passed on from the interfacing layer above it. However, during reception, a compatible device having a similar OSI stack may strip off the headers as the message passes from the lower layers up to the higher layers.

The PHY devices 110 a and 110 b may be configured to handle physical layer requirements, which include, but are not limited to, packetization, data transfer and serialization/deserialization (SERDES), in instances where such an operation is required. Data packets received by the PHY devices 110 a and 110 b from MAC controllers 108 a and 108 b, respectively, may include data and header information for each of the above six functional layers. The PHY devices 110 a and 110 b may be configured to encode data packets that are to be transmitted over the cable 112 and/or to decode data packets received from the cable 112.

The MAC controller 108 a may comprise suitable logic, circuitry, and/or code that may enable handling of data link layer, layer 2, operability and/or functionality in the local link partner 102. Similarly, the MAC controller 108 b may comprise suitable logic, circuitry, and/or code that may enable handling of layer 2 operability and/or functionality in the remote link partner 104. The MAC controllers 108 a and 108 b may be configured to implement Ethernet protocols, such as those based on the IEEE 802.3 standard, for example. Notwithstanding, the invention is not limited in this regard.

The MAC controller 108 a may communicate with the PHY device 110 a via an interface 114 a and with the host 106 a via a bus controller interface 116 a. The MAC controller 108 b may communicate with the PHY device 110 b via an interface 114 b and with the host 106 b via a bus controller interface 116 b. The interfaces 114 a and 114 b correspond to Ethernet interfaces that comprise protocol and/or link management control signals. The interfaces 114 a and 114 b may be multi-rate capable interfaces and/or media independent interfaces (MII). The bus controller interfaces 116 a and 116 b may correspond to PCI or PCI-X interfaces. Notwithstanding, the invention is not limited in this regard.

In operation, PHY devices such as the PHY devices 110 a and 110 b may conventionally transmit data via a fixed number of physical channels at a fixed data rate which may result in network links being underutilized and transmitting IDLE symbols for significant portions of time. In this regard, when the link partners 202 and 204 first establish a connection, they may exchange some preliminary information and/or training signals. In this regard, the link partners 102 and 104 may negotiate a data rate (e.g., 10 Gbps) and duplex mode (e.g., full-duplex) for communicating with each other. Additionally, in order to establish reliable communications, each of the link partners 102 and 104 may need to “train” or adjust various parameters and/or circuitry in a link partner to account for variables such as the type of cabling over which data is being communicated and the environmental conditions (e.g. temperature) surrounding the cabling. Once the link partners are “trained”, they may initially transmit data at 10 Gbps, for example. In this regard, conventional PHY devices may distribute traffic evenly over all available physical channels and may continuously transmit IDLE symbols between packets of actual data. However, based, for example, on link utilization, past or present traffic statistics, and/or available resources (e.g., power, buffer space, processor time, etc.), it may be determined that 10 Gbps may be higher than necessary or desired. Accordingly, controlling the data rate of the connection between the link partners 102 and 104 may enable the link partners 102 and 104 to communicate in a more energy efficient manner. Moreover, while the data rate on the link 112 may be low(er), higher layer functions and/or resources, such as portions of the MAC controller, may be placed into a low(er) power mode. The data rate may be controlled by, for example, controlling a number of physical channels utilized to communicate data, controlling the pulse amplitude modulation (PAM) levels used for signaling, controlling the signal constellation utilized for representing data on the link, and/or controlling the length of time between frames (the inter-frame gap). In this manner, aspects of the invention may enable network designers and/or administrators to customize data rate thresholds of a network link to meet the unique demands of that link.

By controlling a data rate of a network link to meet demands on the link, a fixed data rate may be achieved which may reduce or eliminate issues associated with traffic patterns on links which transmit in bursts. For example, controlling and/or determining traffic attributes (e.g., inter-frame gap times and network latencies) and/or network resources (e.g., buffer capacity and utilization) may be simplified when dealing with fixed rate traffic. Moreover, certain traffic types, such as video and audio streams, may inherently be of a fixed data rate and may thus lend themselves to efficient transmission over a link utilizing a fixed data rate.

FIG. 2 is a block diagram illustrating an exemplary Ethernet over twisted pair PHY device architecture comprising a multi-rate capable physical block, in accordance with an embodiment of the invention. Referring to FIG. 2, there is shown a link partner 200 which may comprises an Ethernet over twisted pair PHY device 202, a MAC controller 204, a host 206, an interface 208, and a bus controller interface 210. The PHY device 202 may be an integrated device which may comprise a multi-rate capable physical layer block 212, one or more transmitters 214, one or more receivers 220, a memory 216, a memory interface 218, and one or more input/output interfaces 222.

The PHY device 202 may be an integrated device that comprises a multi-rate capable physical layer block 212, one or more transmitters 214, one or more receivers 220, a memory 216, a memory interface 218, and one or more input/output interfaces 222. The operation of the PHY device 202 may be the same as or substantially similar to that of the PHY devices 110 a and 110 b disclosed in FIG. 1. In this regard, the PHY device 202 may provide layer 1 (physical layer) operability and/or functionality that enables communication with a remote PHY device. Similarly, the operation of the MAC controller 204, the host 206, the interface 208, and the bus controller 210 may be the same as or substantially similar to the respective MAC controllers 108 a and 108 b, hosts 106 a and 106 b, interfaces 114 a and 114 b, and bus controller interfaces 116 a and 116 b as described in FIG. 1. The MAC controller 204 may comprise a multi-rate capable interface 204 a that may comprise suitable logic, circuitry, and/or code to enable communication with the PHY device 202 at a plurality of data rates via the interface 208.

The multi-rate capable physical layer block 212 in the PHY device 202 may comprise suitable logic, circuitry, and/or code that may enable operability and/or functionality of physical layer requirements. In this regard, the multi-rate capable physical layer block 212 may enable generating the appropriate link discovery signaling utilized for establishing communication with a remote PHY device in a remote link partner. The multi-rate capable physical layer block 212 may communicate with the MAC controller 204 via the interface 208. In one aspect of the invention, the interface 208 may be a media independent interface (MII) and may be configured to utilize a plurality of serial data lanes for receiving data from the multi-rate capable physical layer block 212 and/or for transmitting data to the multi-rate capable physical layer block 212. The multi-rate capable physical layer block 212 may be configured to operate in one or more of a plurality of communication modes, where each communication mode may implement a different communication protocol. These communication modes may include, but are not limited to, Ethernet over twisted pair standards 10BASE-T, 100BASE-TX, 1000BASE-T, 10GBASE-T, and other similar protocols that utilize multiple physical channels between link partners. The multi-rate capable physical layer block 212 may be configured to operate in a particular mode of operation upon initialization or during operation. For example, auto-negotiation may utilize the FLP bursts to establish a rate (e.g. 10 Mbps, 100 Mbps, 1000 Mbps, or 10 Gbps) and mode (half-duplex or full-duplex) for transmitting information.

The multi-rate capable physical layer block 212 may be coupled to memory 216 through the memory interface 218, which may be implemented as a serial interface or a bus. The memory 216 may comprise suitable logic, circuitry, and/or code that may enable storage or programming of information that includes parameters and/or code that may effectuate the operation of the multi-rate capable physical layer block 212. The parameters may comprise configuration data and the code may comprise operational code such as software and/or firmware, but the information need not be limited in this regard. Moreover, the parameters may include adaptive filter and/or block coefficients for use, for example, by the multi-rate capable physical layer block 212 and/or the hybrids 226.

Each of the transmitters 214 a, 214 b, 214 c, 214 d may comprise suitable logic, circuitry, and/or code that may enable transmission of data from the link partner 200 to a remote link partner via, for example, the cable 112 in FIG. 1. The receivers 220 a, 220 b, 220 c, 220 d may comprise suitable logic, circuitry, and/or code that may enable receiving data from a remote link partner. Each of the transmitters 214 a, 214 b, 214 c, 214 d and receivers 220 a, 220 b, 220 c, 220 d in the PHY device 202 may correspond to a physical channel of the cable 112. In this manner, a transmitter/receiver pair may interface with each of the physical channels 224 a, 224 b, 224 c, 224 d. In this regard, the transmitter/receiver pairs may be enabled to provide the appropriate communication rate and mode for each physical channel.

The input/output interfaces 222 may comprise suitable logic circuitry, and/or code that may enable the PHY device 202 to impress signal information onto a physical channel, for example a twisted pair comprising the cable 112 disclosed in FIG. 1. Consequently, the input/output interfaces 222 may, for example, provide conversion between differential and single-ended, balanced and unbalanced, signaling methods. In this regard, the conversion may depend on the signaling method utilized by the transmitter 214, the receiver 220, and the type of medium of the physical channel. Accordingly, the input/output interfaces 222 may comprise one or more baluns and/or transformers and may, for example, enable transmission over a twisted pair. Additionally, the input/output interfaces 222 may be internal or external to the PHY device 202. In this regard, if the PHY device 202 comprises an integrated circuit, then “internal” may, for example, refer to being “on-chip” and/or sharing the same substrate. Similarly, if the PHY device 202 comprises one or more discrete components, then “internal” may, for example, refer to being on the same printed circuit board or being within a common physical package.

In operation, the PHY device 202 may be enabled to transmit and receive simultaneously over up to four or more physical links. Accordingly, the link partner 200 may comprise a number of hybrids 226 corresponding to the number of physical links. Each hybrid 226 may comprise suitable logic, circuitry, and/or code that may enable separating transmitted and received signals from a physical link. For example, the hybrids may comprise echo cancellers, far-end crosstalk (FEXT) cancellers, and/or near-end crosstalk (NEXT) cancellers. Each hybrid 226 in the local link partner 300 may be communicatively coupled to an input/output interface 222.

In operation, the link partner 200 may communicate with a remote partner via the cable 112. For example, for 10 Gbps Ethernet, the link partner 200 may transmit data to and receive data from a remote partner via the physical channels 224 a, 224 b, 224 c, and 224 d. In this regard, when there is no data for the link partner 200 to transmit, then it may transmit IDLE symbols to keep itself and/or the remote partner “trained”. In this manner, power consumption of a network may be largely independent of the amount of actual data being transmitted over the network. Accordingly, controlling the data rate over the cable 112 may enable the link partners 200 to transmit fewer IDLE symbols and thus communicate in a more energy efficient manner.

In various embodiments of the invention, the link partner 200 may disable, or put into a low(er) power state, one or more of the physical channels 224, when those one or more physical channels are not required to meet current and/or future demand of the link. In this manner, transmitters 214, receivers 220, hybrids 226, and/or portions of the multi-rate capable physical layer block 212 associated with the inactive physical channels may be powered down. In various embodiments of the invention, a channel in a low(er) power state a may convey little or no data any may be silent, convey IDLE symbols, and/or convey other energy. In some instances, aspects of the invention may enable placing all channels of a link into a low(er) power state.

In various embodiments of the invention, a data rate of a communication link may be controlled by adjusting the size of a signal constellation. In this regard, a signal constellation utilized to transmit signals on one or more active channels may be reduced to provide lower data rates. For example, a subset of a larger signal constellation may be chosen such that encoding and decoding signals may be less hardware and/or processor intensive. In this manner, portions of the multi-rate capable physical layer block 212 may consume less energy when encoding data utilizing a smaller or different signal constellation. In some instances, all channels of a link may be active and a reduced signal constellation may be utilized

In various embodiments of the invention, a data rate of a communication link may be controlled by adjusting the PAM levels utilized for signaling. For example, in instances such as 10 Gbps Ethernet, where data it typically encoded utilizing a PAM-16 scheme, aspects of the invention may enable switching to PAM-8 or PAM-4 for lower data rates. In this regard, utilizing fewer PAM levels, and thus smaller voltages, may reduce power consumption in the system 200 as well as energy consumed on the link 212.

In various embodiments of the invention, a data rate of a communication link may be controlled by controlling the inter-frame gap time. In this regard, increasing the IFG may reduce the data rate while decreasing the IFG may increase the data rate.

In various embodiments of the invention, all channels of a link may remain active and a data rate on each of the channels may be controlled via one or more of controlling a signal constellation, controlling PAM levels, and/or controlling an IFG.

FIG. 3 is a diagram illustrating an exemplary system enabled for reduced power consumption during periods of low link utilization, in accordance with an embodiment of the invention. Referring to FIG. 3 there is shown four physical channels 300 a, 300 b, 300 c, and 300 d which may exist, for example, between two link partners such as the link partner 200 of FIG. 2. In this regard, power savings may be realized by reducing one or more physical channels to a low(er) power or reduced activity state. For example, in the 10 Gbps system depicted, the data rate may be reduced to 7.5 Gbps, 5 Gbps, or 2.5 Gbps by disabling or putting into a low(er) power state, 1,2, or 3, respectively, of the 4 physical channels 300 a, 300 b, 300 c, and 300 d. Moreover, when transmitting at a lower data rate, aspects of the invention may enable re-starting and/or powering up one or more of the physical channels 300 a, 300 b, 300 c, and 300 d. Aspects of the invention may enable preventing the need for “re-training” and/or reducing the time for “re-training” when powering up or re-starting one or more of the physical channels 300 a, 300 b, 300 c, and 300 d.

FIG. 4 is a block diagram illustrating transmission of signals utilizing a reduced number of signals levels, in accordance with an embodiment of the invention. Referring to FIG. 4 there is shown a data stream 400 comprising three intervals of data transmission 402, 404, and 406. The data stream 400 may be transmitted by a link partner such as the link partners 102 or 104 of FIG. 1. In this regard, each of the intervals of data 402, 404, and 406 may each comprise one or more Ethernet frames.

In the exemplary 1 Gbps Ethernet system shown, PAM-5, with the levels {+2, +1, 0, −1, −2}, may be utilized for representing signals. In this regard, the levels +2, +1, 0, −1, −2 may, for example, map to voltages +1V, +0.5V, 0V, −0.5V, and −1V, respectively. Consequently, levels +2 and −2 may result in increased power consumption due to the higher voltage utilized to represent them. Accordingly, by representing signals with only the levels {+1, −1}, aspects of the invention may enable reducing the power consumption in a network. In another embodiment of the invention, in a 10 Gbps Ethernet system, which typically uses PAM-16, the number of levels may be reduced, for example, to 4, 8, or 12 levels.

In the exemplary operation depicted in FIG. 4, during periods of high link utilization, such as intervals 402 and 406, data may be represented utilizing 5 signal levels, and during periods of low link utilization, such as the interval 404, 2 signal levels may be utilized. In this manner, aspects of the invention may be enabled to determine, for example, required data rates and adjust one or more signal constellations accordingly. For example, a link partner, such as the link partner 200 of FIG. 2 may be enabled to determine necessary data rates to prevent an overflowed buffer. Although an example of 1 Gbps Ethernet with 5 levels is provided, the original constellation size, the reduced constellation size, the original data rate, the reduced data rate, and/or other characteristics of a network and/or data transmission may differ without deviating from the scope of the invention.

FIG. 5 is a diagram illustrating transmission of signals utilizing a reduced signal constellation, in accordance with an embodiment of the invention. In the exemplary embodiment depicted, a 128-DSQ constellation 502, as may be typically used for 10 Gbps Ethernet, may be reduced to a 8-DSQ constellation 504. In this regard, logic, circuitry, and/or code which may encode data may consume less power when encoding data utilizing the 8-DSQ constellation 504 as compared to the 128-DSQ constellation. For example, when utilizing the 8-DSQ constellation, all or a portion of a low density parity check (LDPC) encoder and/or decoder may be disabled, resulting in a large power savings. In various other embodiments of the invention, different signal constellations may be utilized.

FIG. 6 is a diagram illustrating adjusting inter-frame gap to control data rates on an Ethernet link, in accordance with an embodiment of the invention. Referring to FIG. 6, there is shown two exemplary periods of activity in an Ethernet physical channel. In this regard, during period of activity 600, inter-frame gap may be shorter than during period 650. Accordingly, the data rate during period 600 may be higher than the data rate during period 650. In this manner, aspects of the invention may enable altering a communication rate over an Ethernet link by adjusting the inter-frame gap. For example, a subset PHY may control the number of physical channels over which data is communicated between two nodes. However, when one or more physical channels are turned off, a data rate over an Ethernet link may be a non-standardized rate. Accordingly, in instances when a standardized data rate is desired, the inter-frame gap time may be adjusted such that data is communicated at a standardized rate.

The effect of the IFG on the overall data rate may depend on the data being transmitted on the link. For example, if maximum sized Ethernet frames are transmitted, the IFG may represent a smaller percentage of a given time interval, whereas if minimum sized Ethernet frames are transmitted then the IFG may represents a greater percentage of the time interval. Accordingly, to achieve a desired effect on the overall data rate of the link, past, present, and/or predicted frame sizes and/or patterns may be taken into account when adjusting the IFG. The same may be true for the inter-packet gap (IPG) when considering packets.

FIG. 7 is a diagram illustrating data rate transitions on a network link with configurable data rate thresholds, in accordance with an embodiment of the invention. Referring to FIG. 7 waveform 702 may indicate the traffic on a network link during the time interval from t₁ to t₅, and waveforms 704 a, 704 b, 704 c, 704 d may, respectively, indicate the maximum data rate of the link during the time intervals t₁ to t₂, t₂ to t₃, t₃ to t₄, and t₄ to t₅.

Aspects of the invention may enable adjusting the maximum data rate of a network based on traffic on the link during one or more time intervals. In this regard, the data rate of a network link may be reduced by controlling a variety of data rate factors. For example, controllable data rate factors may comprise turning on or off one or more physical channels of the link, altering a the number of levels utilized for signaling, altering a signal constellation utilized for representing signals on the link, and/or adjusting the inter-frame gap time or inter-packet gap time on the link. In this regard, data rate factors may be controlled to allow a number of data rate thresholds which may or may not correspond to standard Ethernet data rates. Additionally, the data rates may be programmable via one or more control signals generated in software, hardware, or a combination thereof.

In the exemplary embodiment of the invention, with reference to FIG. 7, during time interval t₁-t₂, the traffic on the link may be greater than the threshold R₂ but less than the threshold R₁. Accordingly, during time interval t₁-t₂, the link may operate a data rate of R₁. However, at time instant t₂, the traffic on the network may fall below the threshold R₂. Consequently, aspects of the invention may enable reducing energy consumption by reducing the data rate to R₂. In this regard, the data rate may be reduced to R₂ by turning off one or more physical channels comprising the link, altering signal levels, altering the signal constellation, and/or adjusting the inter-frame gap time or inter-packet gap time. At time instant t₃, the traffic on the network may decrease further and may fall below the threshold R₄. Consequently, aspects of the invention may enable reducing energy consumption by reducing the data rate to R₄.

At time instant t₄, the traffic on the network may increase. Consequently, the data rate R₄ may be insufficient to handle the traffic on the link. Accordingly, aspects of the invention may enable increasing the data rate to R₃. In this regard, during the time interval t_(buffer) from when the traffic increases above R₄ to when the system changes the data rate to R₃, buffering techniques may be utilized to prevent dropped packets until the transition from a lower data rate to a higher data rate occurs. In this regard, there may be a tradeoff between buffering capacity and time required to transition between data rates. Moreover, aspects of the invention may enable predicting increases in network traffic based on, for example, past network statistics, characteristics of data being transmitted, time of day, applications running on a node connected to the link, or other factors. In this manner, the data rate may be increased prior to a loss or corruption of data.

Aspects of the invention may enable controlling and/or programming, via hardware, software, or a combination thereof, the number of thresholds and the values of the thresholds. In this regard, a higher number of thresholds may provide increased efficiency. Additionally, the thresholds may be intelligently and/or optimally chosen based on, for example, the type of traffic the link typically carries, the type of nodes the link connects, and applications associated with the link. For example, in instances where the nature of the traffic on a network link results in data rates being either 2.5 Gbps or 7 Gbps, then aspects of the invention may enable selecting thresholds 2.5 Gbps and 7 Gbps, or slightly higher to allow for headroom. In this regard, a network administrator may, for example, customize possible data rates, thresholds for switching between those data rates, and the manner in which data rates are adjusted, on a link by link basis.

FIG. 8 is a flowchart illustrating exemplary steps for establishing and selecting a programmable data rate, in accordance with an embodiment of the invention. Subsequent to start step 802, the exemplary steps may advance to step 804. In step 804, traffic on a network link may be analyzed. In this regard, in various embodiments of the invention, the analysis may be performed by a processor or other computing device and/or by a network administrator. Subsequent to step 804, the exemplary steps may advance to step 806. In step 806, a list of data rates for the link may be established. In this regard, the list of data rates may be established at or above data rates at which the link typically or often operates. Subsequent to step 806, the exemplary steps may advance to step 808. In step 808, a data rate from the list may be chosen for operation of the link. In this regard, the chosen data rate may be a data rate in the list that may be closest to, but greater than, current or expected needs of the link. Subsequent to step 810, the exemplary steps may advance to step 812. In step 812, traffic on the link and/or traffic being prepared for transmission on the link may be monitored. In this manner, in instances that demand on the link may decrease a lower data rate may be selected from the list. Similarly, in instances that demand on the link may increase, a higher data rate may be selected from the list.

Aspects of a method and system for programmable data rate thresholds for energy efficient Ethernet are provided. In this regard a data rate for communicating over a network link, such as the link 112 of FIGS. 1 and 2 may be selected from a list of permissible data rates. The list of permissible data rates may be determined based on traffic associated with the network link. Each of the permissible data rates may be determined based on, for example, past and/or expected traffic on the link, a type of traffic associated with the link, and/or one or more applications associated with the link. The selected data rate may be achieved by controlling a number of physical channels of the link that are utilized for communications over the link, as described with respect to FIG. 3, voltage and/or current levels utilized for signaling on the link, as described with respect to FIG. 4, a signal constellation utilized for representing data on the link as described with respect to FIG. 5, and/or an inter-frame gap or inter-packet gap utilized on the link as described with respect to FIG. 6. The selected data rate may be the lowest rate in the list that may still be greater than a demand on the link, as described with respect to FIG. 7. A first portion of the list may be utilized for ingress communication and a second portion of the list may be utilized for egress communication.

Another embodiment of the invention may provide a machine-readable storage, having stored thereon, a computer program having at least one code section executable by a machine, thereby causing the machine to perform the steps as described herein for configurable data rate threshold for energy efficient Ethernet.

Accordingly, the present invention may be realized in hardware, software, or a combination of hardware and software. The present invention may be realized in a centralized fashion in at least one computer system, or in a distributed fashion where different elements are spread across several interconnected computer systems. Any kind of computer system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware and software may be a general-purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein.

The present invention may also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein, and which when loaded in a computer system is able to carry out these methods. Computer program in the present context means any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following: a) conversion to another language, code or notation; b) reproduction in a different material form.

While the present invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from its scope. Therefore, it is intended that the present invention not be limited to the particular embodiment disclosed, but that the present invention will include all embodiments falling within the scope of the appended claims. 

1. A method for networking, the method comprising: selecting, from a list of permissible data rates for operating a network link, a data rate for handling traffic over said network link, wherein each of said permissible data rates is determined based on traffic associated with said network link; and communicating over said network link at said selected data rate.
 2. The method according to claim 1, wherein said each of said permissible data rates is determined based on past and/or expected traffic on said network link.
 3. The method according to claim 1, wherein said each of said permissible data rates is determined based on a type of traffic associated with said network link.
 4. The method according to claim 1, wherein said each of said permissible data rates is determined based on one or more applications associated with said network link.
 5. The method according to claim 1, comprising adjusting said selected data rate by controlling a number of physical channels of said network link utilized to transfer information.
 6. The method according to claim 1, comprising adjusting said selected data rate by controlling voltage and/or current levels utilized for signaling on said network link.
 7. The method according to claim 1, comprising adjusting said selected data rate by controlling a signal constellation utilized for representing data on said network link.
 8. The method according to claim 1, comprising adjusting said selected data rate by controlling an inter-frame gap utilized on said network link.
 9. The method according to claim 1, comprising selecting, from said list of permissible data rates, a lowest data rate that is greater than a demand on said network link.
 10. The method according to claim 1, wherein a first portion of said list of permissible data rates is utilized for ingress communication and a second portion of said list of permissible data rates is utilized for egress communication.
 11. A system for networking, the system comprising: one or more circuits that enable selection of, from a list of permissible data rates for operating a network link, a data rate for handling traffic over said network link, wherein each of said permissible data rates is determined based on traffic associated with said network link; and said one or more circuits enable communication over said network link at said selected data rate.
 12. The system according to claim 11, wherein said each of said permissible data rates is determined based on past and/or expected traffic on said network link.
 13. The system according to claim 11, wherein said each of said permissible data rates is determined based on a type of traffic associated with said network link.
 14. The system according to claim 11, wherein said each of said permissible data rates is determined based on one or more applications associated with said network link.
 15. The system according to claim 11, wherein said one or more circuits enable adjustment of said selected data rate by controlling a number of physical channels of said network link utilized to transfer information.
 16. The system according to claim 11, wherein said one or more circuits enable adjustment of said selected data rate by controlling voltage and/or current levels utilized for signaling on said network link.
 17. The system according to claim 11, wherein said one or more circuits enable adjustment of said selected data rate by controlling a signal constellation utilized for representing data on said network link.
 18. The system according to claim 11, wherein said one or more circuits enable adjustment of said selected data rate by controlling an inter-frame gap utilized on said network link.
 19. The system according to claim 11, wherein said one or more circuits enable selection of, from said list of permissible data rates, a lowest data rate that is greater than a demand on said network link.
 20. The system according to claim 11, wherein a first portion of said list of permissible data rates is utilized for ingress communication and a second portion of said list of permissible data rates is utilized for egress communication.
 21. A machine-readable storage having stored thereon, a computer program having at least one code section for networking, the at least one code section being executable by a machine for causing the machine to perform steps comprising: selecting, from a list of permissible data rates for operating a network link, a data rate for handling traffic over said network link, wherein each of said permissible data rates is determined based on traffic associated with said network link; and communicating over said network link at said selected data rate.
 22. The machine-readable storage according to claim 21, wherein said each of said permissible data rates is determined based on past and/or expected traffic on said network link.
 23. The machine-readable storage according to claim 21, wherein said each of said permissible data rates is determined based on a type of traffic associated with said network link.
 24. The machine-readable storage according to claim 21, wherein said each of said permissible data rates is determined based on one or more applications associated with said network link.
 25. The machine-readable storage according to claim 21, wherein said at least one code section comprises code for adjusting said selected data rate by controlling a number of physical channels of said network link utilized to transfer information.
 26. The machine-readable storage according to claim 21, wherein said at least one code section comprises code for adjusting said selected data rate by controlling voltage and/or current levels utilized for signaling on said network link.
 27. The machine-readable storage according to claim 21, wherein said at least one code section comprises code for adjusting said selected data rate by controlling a signal constellation utilized for representing data on said network link.
 28. The machine-readable storage according to claim 21, wherein said at least one code section comprises code for adjusting said selected data rate by controlling an inter-frame gap utilized on said network link.
 29. The machine-readable storage according to claim 21, wherein said at least one code section comprises code for selecting, from said list of permissible data rates, a lowest data rate that is greater than a demand on said network link.
 30. The machine-readable storage according to claim 21, wherein a first portion of said list of permissible data rates is utilized for ingress communication and a second portion of said list of permissible data rates is utilized for egress communication. 